Nucleus augmentation delivery device and technique

ABSTRACT

A method of performing a procedure on an intervertebral disc includes inserting a cannulated delivery tube through an opening in an annulus fibrosus of the intervertebral disc, positioning an expandable portion of the tube within the opening in the annulus fibrosus, expanding the expandable portion into contact with the annulus fibrosus about the opening to create a seal between the expandable portion and the annulus fibrosus, performing a procedure through the cannulated delivery tube within the annulus fibrosis, removing the tube, and closing the opening in the annulus fibrosus.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/260,768, filed Oct. 27, 2005, which is incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to a device and method for determiningthe volume of intervertebral disc augmentation material needed tocomplete disc augmentation and the material's subsequent delivery. Asecond goal of this invention is to reduce leakage incurred whendispensing materials from a rigid cannula by improving the fit and fillof the annular wall defect.

2. Related Art

Some techniques for nucleus pulposus injection of materials like theSINUX® silicone disc augmentation material, utilize an injection cannulaof rigid outer diameter to insert into the annular wall defect.Determination of the excised nucleus pulposus tissue is currentlyattempted via weight and/or volumetric measurement of the tissuefollowing removal. Corresponding amounts of nucleus replacement materialare injected into the disc space. Leakage of the injected material is aknown issue when excess nucleus pulposus replacement material is added,correspondingly inadequate replacement of the nucleus can allow fordevice expulsion or improper functional spinal unit balance. Thereforeaccurate determination of the removed nucleus pulposus volume remains tobe a challenge. Another issue present is the potential leakage of theinjected material that may arise from an inadequate fit between therigid injection cannula and the varying size annular wall defect(s).

Several nucleus pulposus and annular repair patents have been appliedand issued. U.S. Patent Application Publication No. 2004/0068268discloses cannulated distractors for maintaining disc height duringreplacement or augmentation of the spinal disc. U.S. Patent ApplicationPublication No. 2003/0220649 describes interior liners and membranessuch as balloons for in situ formation of nucleus replacement oraugmentation materials. Bao et al. (European Cells and Materials, Vol.10 Suppl. 3, 2005, p. 3), disclose assessing the shape and volume of thenucleus cavity in total nucleus removal procedures using an imagingballoon filled with contrast medium and fluoroscopic balloon imagestaken from multiple directions. However, none have been found that teachannular sealing for volumetric determination of the evacuated disc spaceand/or subsequent delivery of the disc replacement or augmentationmaterial as hereinafter disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 a-1 f depict one embodiment of this invention using a cannulawith a conformable tip.

FIGS. 2 a-2 b depict another embodiment of this invention using acannula with an expandable tip. FIGS. 3 a-3 b depict yet anotherembodiment of this invention using a cannula with an inflatable balloontip.

FIGS. 4 a-4 f depict another embodiment of this invention using acannula with an anti backflow check valve.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, a method ofperforming a procedure on an intervertebral disc comprises inserting acannulated delivery tube through an opening in an annulus fibrosus ofthe intervertebral disc, positioning an expandable portion of the tubewithin the opening in the annulus fibrosus, expanding the expandableportion into contact with the annulus fibrosus about the opening tocreate a seal between the expandable portion and the annulus fibrosus,performing a procedure through the cannulated delivery tube within theannulus fibrosis, removing the tube, and closing the opening in theannulus fibrosus. The procedure performed may include injecting throughthe tube and the sealed opening in the annulus fibrosus an amount of aflowable nucleus pulposus replacement material directly into the annulusfibrosus. The expandable portion may comprise an expandable elastomericgasket, in one embodiment, and the expandable portion may comprise aninflatable balloon, in another embodiment.

One advantage of this invention is its relatively easy determination ofthe volume of nucleus pulposus material removed as well as sealing ofthe annular wall defect to prevent intra-operative material leakagecommon when greater amounts than needed of nucleus pulposus material areinjected to correct a disc defect.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Determination of the volume of nucleus pulposus material removed fromthe disc and prevention of leakage incurred during injection of nuclearreplacement and/or augmentation materials are important aspects ofintervertebral disc repair. Excessive injection and/or leakage of thereplacement material(s) can initiate re-herniation or prompt herniationof the disc in another weakened annular location. Both of these failuremodes can irritate neighboring tissues, including nerve roots, promptingadditional pain and/or re-operation.

Insufficient nucleus pulposus injection can allow for continued discheight loss potentially leading to revision surgery.

The basic premise of this invention is that following a discectomy, acannulated device is inserted into the surgically created annular walldefect. The annulus is sealed such that a known quantity of saline orother material can be injected and subsequently aspirated to determinevolume of nucleus pulposus tissue removed. An equal volume of nucleuspulposus replacement material is injected or packed into the nucleuspulposus cavity through the device.

In making the volumetric determination of the defect to be repaired, agraduated syringe of known volume of volumetric material may be placedin to the cannulated device and injected into the intervertebral defectspace, for example. Pressure can be applied to the material andmonitored to insure full fill of small defects. A check valve with knownpressure release can be utilized to ensure filling to a known pressure.

Suitable volumetric materials can be viscous and non-viscous includingsaline, gels, polymers, etc. Volumetric materials can be radio-opaquecontrast agents, allowing fluoroscopic viewing during injection into thedisc to a known pressure.

Examples of annular sealing techniques include: a conformable injectiontip; an activated injection tip, and a balloon catheter injection tip.An optional embodiment of an internal valve to prevent backflow ofeither the saline or the nucleus pulposus replacement material is alsodisclosed. All sealing devices and methods maybe deployedextra-annularly, intra and/or inter-annularly (i.e., with respect to theannulus).

FIGS. 1 a-1 f, describe an injection cannula 10 with a conformable tipsuch as a soft elastomeric or foam gasket 12 around the injection tip ofthe cannula which is used to seal the annular defect. More specificallyFIG. 1 a depicts cannula 10 approaching surgically created hole ordefect 4 in annulus fibrosus 2. The intervertebral disc space 3 formedby excision of nucleus pulposus is shown as empty. Adjacent vertebralbody 1 shows the relative relationship affected disc to vertebral body1. Gasket 12 can be comprised of varying shapes and geometries (ring,hourglass, tapered, etc.). Examples of suitable elastomeric or foammaterials include but are not limited to thermoplastic elastomers,polypropylenes, polyethylenes, silicones, polyurethanes, latex, alloysand blends thereof

FIG. 1 b shows cannula 10 being advanced into defect 4. FIG. 1 c depictsthe cannula 10 firmly engaged into defect 4 by virtue of gasket 12 so asto form an annular seal. FIG. 1 d shows the volumetric material beingintroduced through cannula 10 into intervertebral disc space 3. Theamount of volumetric material is measured or metered so as to determinethe volume of cleared intervertebral disc space 3 that needs to befilled with a nucleus pulposus replacement or augmentation material.Once the volume of intervertebral disc space 3 is determined,intervertebral disc space 3 is evacuated in a preferred embodimentthrough cannula 10 as depicted in FIG. 1 d. It should be noted that thevolumetric material may be evacuated through another path, such asthrough another hole in the annulus fibrosus. FIG. 1 e depicts theintroduction of nucleus pulposus replacement or augmentation materialthrough cannula 10 into intervertebral disc space 3. Once intervertebraldisc space 3 is filled to the appropriate volume, cannula 10 is removedleaving annular hole or defect 4 open as shown in FIG. 1 f. Defect 4 maybe closed by any suitable closure techniques known in the art such asthrough use of an annular plug or by surgical suturing.

FIGS. 2 a-2 b describe one embodiment of a device of this inventionwherein a volumetric material delivery device comprises an expandableelastomeric tip or foam gasket. More particularly, FIG. 2 a depicts thedevice comprising inner cannula 20 and outer cannula 18. Disposedbetween cannula 18 and 20 is elastomeric gasket 16. FIG. 2 b shows thedevice in activation wherein the relative position of internal cannula20 has changed with respect to outer cannula 18 so as to cause gasket 16to bulge or radially expand and thereby form a firm seal of annulardefect 4 and allow for substantially leak proof delivery of thevolumetric material. The bulging of gasket 16 may be caused, forexample, by pushing external cannula 18 to create the desired seal, orconversely by pulling of e internal cannula 20 to expand for the desiredamount of seal. Multiple shapes and materials for gasket 16 may beutilized as described above for gasket 12.

FIGS. 3 a and 3 b describe yet another device for forming a seal via aballooning tip. Specifically, FIG. 3 a describes a cross-sectional viewof cannula 10 comprising catheter tube 32 and inflatable balloon 30.Tube 32 acts a passageway to provide air or gas to the annular balloon30 for inflation. FIG. 3 b shows the device in operation wherein balloon30 has been inflated to firmly seal annulus fibrosus prior to volumetricmaterial being introduced into intervertebral disc space 3. Balloon 30may be produced from any thin biocompatible flexible polymer known inthe art.

FIGS. 4 a-4 f depict a preferred embodiment of this invention whichutilizes an internal check valve to preclude backflow of eithervolumetric material and/or the nucleus pulposus replacement material.Referring to FIG. 4 a, cannula 10 comprises anti-backflow valve 40 andannular sealing means 42. It should be noted that annular sealing means42 may be any of the above described sealing techniques, e.g.,conformable tip, expanding gasket or inflating balloon. Valve 40 may beactivated to allow for aspiration and/or removal of the volumetricmaterial or excess nucleus pulposus replacement or augmentationmaterial.

A further preferred embodiment as shown in FIG. 4 b, a cannulated stylet50 is inserted into the cannula 10 which has been sealed into annulardefect 4. In dispensing volumetric material into intervertebral discspace 3, stylet 50 is advanced, as depicted in FIG. 4 c to permit entryinto intervertebral space 3. Once the amount of volumetric material hasbeen determined, stylet 50 is used in reverse fashion to withdraw thevolumetric materials such as through aspiration, as shown in FIG. 4 d.Once intervertebral space 3 has been evacuated of the volumetricmaterial, the nucleus replacement or augmentation material is injectedinto intervertebral disc space 3 as shown in FIG. 4 e. Finally, FIG. 4 fshows intervertebral disc space 3 filled with the appropriate volume ofnucleus replacement or augmentation material with cannula 10 having beenremoved leaving annular hole or defect 4. Defect 4 may be closed by anysuitable closure techniques known in the art such as through use of anannular plug or by surgical suturing. While this one technique for valveactivation has been shown by insertion of the tip of an injector orstylet into the valve to facilitate opening, any other known techniquescommon to valve technology may be employed in activating anti-back flowvalve 40.

Suitable materials for use as the nucleus pulposus replacement oraugmentation material may be of any known type. Examples of suchmaterials include, but are not limited to polyethylenes, silicones,polyurethanes, metallics, ceramics, collagen, hydrogels, for example.

It should be understood that the foregoing disclosure and description ofthe present invention are illustrative and explanatory thereof andvarious changes in the size, shape and materials as well as in thedescription of the preferred embodiment may be made without departingfrom the spirit of the invention. For example, it is envisioned thatthis invention may be applied to correcting defects in otherarticulating joints were volumetric determination of a defect is abenefit, such as with knees, hips, shoulders, elbow capsules as bestexamples, but also to facets, ankles, wrists, hand, and digits.

1. A method of delivering a nucleus pulposus replacement materialcomprising: inserting a cannulated delivery tube through an opening inan annulus fibrosus of an intervertebral disc, the cannulated deliverytube including an inflatable balloon; positioning the inflatable balloonwithin the opening in the annulus fibrosus; expanding the inflatableballoon into contact with the annulus fibrosus about the opening tocreate a seal between the balloon and the annulus fibrosus; deliveringthrough the tube and the sealed opening in the annulus fibrosus anamount of a nucleus pulposus replacement material directly into theannulus fibrosus and not into an implant placed in the annulus fibrosus,the nucleus pulposus replacement material contacting an inner wall ofthe annulus fibrosis; removing the tube; and closing the opening in theannulus fibrosus.
 2. The method of claim 1, wherein the inflatableballoon is positioned extra-annularly.
 3. The method of claim 1, whereinthe inflatable balloon is positioned intra-annularly.
 4. The method ofclaim 1, wherein the inflatable balloon is positioned inter-annularly.5. The method of claim 1, wherein the cannulated delivery tube furthercomprises a check valve to prevent backflow of the nucleus pulposusreplacement material.
 6. The method of claim 1, wherein the nucleuspulposus replacement material comprises at least one of polyethylenes,silicones, polyurethanes, metallics, ceramics, collagen, and hydrogels.7. The method of claim 1, wherein the nucleus pulposus replacementmaterial is injected into the annulus fibrosus through the tube.
 8. Themethod of claim 1, wherein the nucleus pulposus replacement material ispacked into the annulus fibrosus through the tube.
 9. A method ofdelivering a nucleus pulposus replacement material comprising: insertinga cannulated delivery tube through an opening in an annulus fibrosus ofthe intervertebral disc, the cannulated delivery tube including anexpandable portion; expanding the expandable portion of the tube againstthe annulus fibrosus about the opening to create a seal between theexpanded portion of the tube and the annulus fibrosus and thereby sealthe opening in the annulus fibrosus; and delivering through the tube andthe sealed opening in the annulus fibrosus an amount of nucleus pulposusreplacement material directly into the annulus fibrosis and not into animplant in the disc, the nucleus pulposus replacement materialcontacting an inner wall of the annulus fibrosis.
 10. The method ofclaim 9, wherein the expandable portion comprises an expandableelastomeric gasket.
 11. The method of claim 9, wherein the expandableportion comprises an inflatable balloon.
 12. The method of claim 9,wherein the cannulated delivery tube further comprises a check valve toprevent backflow of the nucleus pulposus replacement material.
 13. Themethod of claim 9, wherein the nucleus pulposus replacement materialcomprises at least one of polyethylenes, silicones, polyurethanes,metallics, ceramics, collagen, and hydrogels.
 14. The method of claim 9,wherein the nucleus pulposus replacement material is injected into theannulus fibrosus through the tube.
 15. The method of claim 9, whereinthe nucleus pulposus replacement material is packed into the annulusfibrosus through the tube.
 16. A method of delivering a nucleus pulposusreplacement material comprising: inserting a cannulated delivery tubethrough an opening in an annulus fibrosus of an intervertebral disc, thecannulated delivery tube including an expandable portion; positioningthe expandable portion within the opening in the annulus fibrosus;expanding the expandable portion into contact with the annulus fibrosusabout the opening to create a seal between the expandable portion andthe annulus fibrosus; delivering through the tube and the sealed openingin the annulus fibrosus an amount of a nucleus pulposus replacementmaterial directly into the annulus fibrosus and not into an implantplaced in the annulus fibrosus, the nucleus pulposus replacementmaterial contacting an inner wall of the annulus fibrosis; removing thetube; and closing the opening in the annulus fibrosus.
 17. The method ofclaim 16, wherein the expandable portion is positioned extra-annularly.18. The method of claim 16, wherein the expandable portion is positionedintra-annularly.
 19. The method of claim 16, wherein the expandableportion is positioned inter-annularly.
 20. The method of claim 16,wherein the expandable portion tube further comprises a check valve toprevent backflow of the nucleus pulposus replacement material.
 21. Themethod of claim 16, wherein the expandable portion comprises anexpandable elastomeric gasket.
 22. The method of claim 16, wherein thenucleus pulposus replacement material comprises at least one ofpolyethylenes, silicones, polyurethanes, metallics, ceramics, collagen,and hydrogels.
 23. The method of claim 16, wherein the nucleus pulposusreplacement material is injected into the annulus fibrosus through thetube.
 24. The method of claim 16, wherein the nucleus pulposusreplacement material is packed into the annulus fibrosus through thetube.
 25. A method of performing a procedure on an intervertebral disccomprising: inserting a cannulated delivery tube through an opening inan annulus fibrosus of the intervertebral disc, the cannulated deliverytube including an expandable portion; positioning the expandable portionwithin the opening in the annulus fibrosus; expanding the expandableportion into contact with the annulus fibrosus about the opening tocreate a seal between the expandable portion and the annulus fibrosus;performing a procedure through the cannulated delivery tube within theannulus fibrosis; removing the tube; and closing the opening in theannulus fibrosus.
 26. The method of claim 25 wherein performing theprocedure includes delivering through the tube and the sealed opening inthe annulus fibrosus an amount of a nucleus pulposus replacementmaterial directly into the annulus fibrosus.
 27. The method of claim 26,wherein the nucleus pulposus replacement material is injected into theannulus fibrosus through the tube.
 28. The method of claim 26, whereinthe nucleus pulposus replacement material is packed into the annulusfibrosus through the tube.
 29. The method of claim 25, wherein theexpandable portion comprises an expandable elastomeric gasket.
 30. Themethod of claim 25, wherein the expandable portion comprises aninflatable balloon.